The thing that I would want most in this movie would be Omega Supreme VS Trypticon/Unicron/someothergiantDecepticon in space while Autobots and Decepticons fight IN SPACE [or in the moon] for their lives.

Michael Bay would find the perfect translation from the word AWESOME to the screen if he made that Final Showdown.

It was rather disappointing that we didn't get space ships in the first movie much less a big space battle. Then in the second film we got a space ship but it was already all wrecked so we didn't know if there was a big fight or it was just bad driving.

Visually a good space battle between ships is kind of hard to pull off, but Bay's strongest point is his ability to make action scenes work so it would be cool to see him tackle something difficult like that at last.

I believe TF3 is about America taking the Ark and the old Autobot from the moon back into the earth by passing thru space.

My guess is the Decepticons manage to repair the Nemesis which shows up over Chicago where the battle takes place. The Autobots probably will need to repair the Ark also to defend themselves against the invading Nemesis.

I wouldn't get your hopes up too high, guys. We know the big climax takes place in Chicago.

Drama is supposed to build, so probably Bay doesn't give us an extravagant space battle before that, or the end battle just winds up looking lame by comparison.

We had the re-entry scene in part 1, and a little more space with the "Nemesis" in part 2. Probably part 3 gives us a similar upping of the space quotient, but it'll still be largely Earth-set action, I imagine.

The Ark on the moon must've been dismantled to bring it to earth. In Chicago, my guess is the Autobots might be using parts of the Ark to help them fight against the invading Nemesis spaceship which must've been used to transport tons of invading Decepticon clones. The Nemesis ship will probably be blasting Chicago to pieces also. Some fixed weapon from the Ark will probably be needed to bring down the Nemesis so I hope everyone watches out for their heads when the Nemesis falls. After the Nemesis falls on Chicago, people will probably be selling parts of the Nemesis on ebay. Sam will probably sell parts of the Ark on ebay to finance his upcoming marriage.

Based on the new Voyager OP toy, I'm thinking that Optimus is going to go out into space and we'll get an action sequence there. It won't be a huge, epic battle but maybe he'll drop out of the space shuttle, land on the moon and race some Decepticons to the Arc, taking a few of their faces on the way.

I'm not expecting a massive battle though, maybe something about like the Forest Battle in ROTF.